1. Field of the Invention
The present invention relates to a cassette for an image forming device used for supporting sheets fed to or sheets received from an electrophotographic apparatus (e.g. a printer, a laser beam printer, a facsimile machine, a complex image forming device, etc). In particular, the present invention relates to an expandable paper cassette.
2. Description of the Related Art
In a contemporary image forming device the sheets fed sequentially, one by one, by finger. A pick up roller loads paper from a sheet feeding tray, and transfers paper to feeding paper. Then, an image forming process occurs as the papers fed toward a sheet discharging roller. Once the sheets have passed through a sheet discharging, roller they are loaded on paper cassette. Thus, an image forming device may be designed to use one of a variety of paper cassette, also known as stackers. The dimensions of the stackers may have a great effect on the size and shape of the machinery.
Nowadays, the image forming machinery may include a folded type stacker of the size corresponding to the sheet size, conforming to a continuing trend toward miniaturized the machinery size. Furthermore, in a case of supporting the sheets fed, the stacker should be sized substantially equal to the sheet size. Thus, the general tendency of the stacker is to embody the stacker even in a smaller space than the sheet size. In a contemporary stacker, when the sheet is discharged using the machinery, the mounting space of the stacker has been minimized by the mounting of a 2 stage or 3 stage structure and forming a guide thereon, thus to "pull" and "push" (a sliding type) it However, this stacker has the problem that until the size of the stacker is equal to with, or lager that of the sheet positioned on the stacker, the stacker will not function properly. As a consequence, since the stacker has an effect on the entire size of the machinery, the substantial mounting space of the machinery should be widened. Examples of this contemporary practice are shown in Petechia (U.S. Pat. No. 5,573,234, Dual Mode Sheet Feeder, Nov. 12, 1996) which discusses a mode of operation in which two sheets are supported side by side. Alteratively, a single sheet feeder mounted movably in the sheet feeding apparatus may be employed to advance successive sheets from each of the stack of sheets. Suda (U.S. Pat. No. 5,565,9709, Image Forming Apparatus, Oct. 15, 1996) discusses a first accommodating cassette for accommodating sheets, and a second accommodating cassette arranged above the first accommodating cassette and adapted to accommodate sheets. A curl correction device causes sheets from different cassettes to bend in the same direction. Kato et al. (U.S. Pat. No. 5,512,928, Information Printing System Having Information Processing Apparatuses And Printer Including Printing Medium Cassettes, Apr. 30, 1996) discusses a printing paper cassette detachment inhibition mechanism unit inhibiting the detachment of the printing paper cassette when the printing paper in the printing paper cassette has been selected for use by one the hosts. A selected printing paper cassette display unit is provided on the laser beam printer and displays the selected printing paper cassette. Amman (U.S. Pat. No. 5,314,177, Sheet Stacking Apparatus, May 24, 1994) discusses a sheet stacking apparatus having a shutter mechanism. When these shutter downward and upward movements are repeatedly performed, stacking can be performed stably, and the sheets discharged from the lower bottom of the stacking safe can be collected in the upper portion of the stacking safe. Kitajima et al. (U.S. Pat. No. 5,156,386, Original Document Feeder, Oct. 20, 1992) discusses a document feeder with a first sheet path for guiding a document from the stacker, along wit the two other sheet paths. Docry (U.S. Pat. No. 4,508,447, Alternative Feeding Document Recirculation, Apr. 2, 1985) discusses separating the sheet of document sheets into two half-sets of alternate page document sheets, odd and even, and restacking the half-sets respectively in the two document trays. Upon the study of contemporary practice and art, I find that there is a need for an effective and improved stacking apparatus, especially the stacking apparatus with such mountings of sheet supports as in the present invention.